1. Technical Field
The present invention relates to printed circuit boards in general, and, in particular, to multilayer printed circuit boards. Still more particularly, the present invention relates to a multilayer printed circuit board having via arrangements for reducing crosstalk among vias.
2. Description of Related Art
A printed circuit board (PCB) typically includes a number of conductive layers (hereinafter referred to as “layers”) separated by insulation such as FR4. Electronic components mounted on one or more surfaces of the PCB can be functionally interconnected through the conductive layers. Routing traces are commonly used to carry signals transmitted among the electronic components mounted on the PCB. Some PCBs have multiple layers of routing traces to accommodate all of the interconnections.
Traces located within different layers of a multilayer PCB are typically connected electrically by vias formed within the PCB. A via can be made by making a hole through some or all the layers within a PCB and the interior hole surface is then coated or plated with an electrically conductive material. A via that connects all layers of a PCB, including the outer layers, is called a through via.
Due to the proximity of vias within a PCB, objectionable crosstalk may occur between one set of vias that are capable of providing the source for coupled energy to another set of vias. Consequently, it would be desirable to provide an improved multilayer printed circuit board with reduced crosstalk among vias.